Re: [PATCH] RDMA/irdma: Improve the way 'cqp_request' structures are cleaned when they are recycled

[Christophe JAILLET]

Le 20/07/2021 à 14:23, Leon Romanovsky a écrit :
> On Mon, Jul 19, 2021 at 07:02:15PM +0200, Christophe JAILLET wrote:
> > A set of IRDMA_CQP_SW_SQSIZE_2048 (i.e. 2048) 'cqp_request' are
> > pre-allocated and zeroed in 'irdma_create_cqp()' (hw.c).  These
> > structures are managed with the 'cqp->cqp_avail_reqs' list which keeps
> > track of available entries.
> >
> > In 'irdma_free_cqp_request()' (utils.c), when an entry is recycled and goes
> > back to the 'cqp_avail_reqs' list, some fields are reseted.
> >
> > However, one of these fields, 'compl_info', is initialized within
> > 'irdma_alloc_and_get_cqp_request()'.
> >
> > Move the corresponding memset to 'irdma_free_cqp_request()' so that the
> > clean-up is done in only one place. This makes the logic more easy to
> > understand.
>
> I'm not so sure. The function irdma_alloc_and_get_cqp_request() returns
> prepared cqp_request and all users expect that it will returned cleaned
> one. The reliance on some other place to clear part of the structure is
> prone to errors.

Ok, so maybe, moving:
	cqp_request->request_done = false;
	cqp_request->callback_fcn = NULL;
	cqp_request->waiting = false;
from 'irdma_free_cqp_request()' to 'irdma_alloc_and_get_cqp_request()' 
to make explicit what is reseted makes more sense?

From my point of view, it is same same: all (re)initialization are done 
at 1 place only.

This would also avoid setting 'waiting' twice (once to false in 
'irdma_free_cqp_request()' and one to 'wait' 
'irdma_alloc_and_get_cqp_request()')


CJ
> Thanks
>
> > This also saves this memset in the case that the 'cqp_avail_reqs' list is
> > empty and a new 'cqp_request' structure must be allocated. This memset is
> > useless, because the structure is already kzalloc'ed.
> >
> > Signed-off-by: Christophe JAILLET <christophe.jaillet-39ZsbGIQGT5GWvitb5QawA@xxxxxxxxxxxxxxxx>
> > ---
> >   drivers/infiniband/hw/irdma/utils.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/infiniband/hw/irdma/utils.c b/drivers/infiniband/hw/irdma/utils.c
> > index 5bbe44e54f9a..66711024d38b 100644
> > --- a/drivers/infiniband/hw/irdma/utils.c
> > +++ b/drivers/infiniband/hw/irdma/utils.c
> > @@ -445,7 +445,6 @@ struct irdma_cqp_request *irdma_alloc_and_get_cqp_request(struct irdma_cqp *cqp,
> >   
> >   	cqp_request->waiting = wait;
> >   	refcount_set(&cqp_request->refcnt, 1);
> > -	memset(&cqp_request->compl_info, 0, sizeof(cqp_request->compl_info));
> >   
> >   	return cqp_request;
> >   }
> > @@ -475,6 +474,7 @@ void irdma_free_cqp_request(struct irdma_cqp *cqp,
> >   		cqp_request->request_done = false;
> >   		cqp_request->callback_fcn = NULL;
> >   		cqp_request->waiting = false;
> > +		memset(&cqp_request->compl_info, 0, sizeof(cqp_request->compl_info));
> >   
> >   		spin_lock_irqsave(&cqp->req_lock, flags);
> >   		list_add_tail(&cqp_request->list, &cqp->cqp_avail_reqs);
> > --
> > 2.30.2